1. Field of the Invention
The present invention is related to a communication network system that comprises either one or a plurality of ring systems, wherein a plurality of node devices and a control node device that controls these node devices are connected by a ring-shaped circuit with communication being carried out between an arbitrary number of node devices or between communication terminals connected to each of the node devices through the ring circuit. In particular, the present invention is related to improvements in the transmission relay portion between each of the ring systems when a plurality of the ring systems are provided and to improvements in a loopback control method that deals with expansion and reduction or fault restoration of node devices without interrupting communication in the ring systems.
2. Description of the Related Art
Communication network systems have been considered in which a plurality of node devices which have an ATM (asynchronous transfer mode) switching function are arranged in a ring shape through the ring circuits such as optical fiber used as a system configuration such as a railroad management system or a roadway management system. And in addition, after connecting local communication terminals such as monitoring cameras or monitoring devices to each of these nodes, data between each of the local communication terminals is transmitted and received through each of the node devices by establishing a plurality of virtual communication paths in a ring shape for the ring circuits and using these communication paths.
FIG. 32 shows the basic configuration of this type of communication network system. This system comprises connecting node devices 10A, 10B, 10C, 10D, 10E and network control device 9 that controls each of these node devices 10A, 10B, 10C, 10D, 10E in a ring shape through the ring circuits that uses, for example, optical fiber.
In a ring system that comprises this type of connection format, node devices 10A, 10B, 10C, 10D, 10E (hereinafter referred to as ring nodes) are actualized using a communication device that has an ATM switching function. Further, network control device 9 (hereinafter referred to as control node) actualized using a communication device that adds an additional function to the ATM switching function that controls the ring nodes 10A, 10B, 10C, 10D, 10E.
Either one or a plurality of local communication terminals can be connected to each ring node 10A, 10B, 10C, 10D, 10E and control node 9. Only local communication terminal 11-1 (connected to ring node 10D) and local communication terminal 11-2 (connected to ring node 10E) are shown in this figure.
Communication between these local communication terminals 11 (11-1, 11-2, xe2x80x94) can be carried out by means of a ring-shaped circuit formed between the ring nodes 10A, 10B, 10C, 10D, 10E and control node 9.
In other words, in this system, a ring is actualized by means of connecting each ring node 10A, 10B, 10C, 10D, 10E and control node 9 using a bi-directional circuit 6. In detail, control node 9 and ring node 10A are connected by a bidirectional circuit comprising circuit 61-1 and circuit 62-6. Further, the gap between ring node 10A and ring node 10B is connected by a bi-directional circuit comprising circuit 61-2 and circuit 62-5. Hereinafter, the gap between ring node 10B and ring node 10C, the gap between ring node 10C and ring node 10D, the gap between ring node 10D and ring node 10E and the gap between ring node 10E and control node 9 are also the same.
Because of this, this system comprises a ring with a direction defined as clockwise comprising circuits 61-1, 61-2, 61-3, 61-4, 61-5, 61-6 and a ring with a direction defined as counterclockwise comprising circuits 62-1, 62-2, 62-3, 62-4, 62-5, 62-6.
In a ring system with this configuration, communication between these local communication terminals 11 is achieved through bi-directional communication that uses a clockwise circuit in an ordinary state. The counterclockwise circuit is operated in a mode reserved for use in a loopback for a circuit fault.
In recent years demands have been increasing to construct network systems which cover a wider range utilizing the ring system shown in FIG. 32. A conventional communication network system that meets these demands has the type of configuration shown in FIG. 33.
This FIG. 33 shows an example of the configuration of a network system comprising three ring networks A, B, C which for the basis of the ring system shown in FIG. 32. In this figure, ring system A comprises six ring nodes 10A-1, 10A-2, 10A-3, 10A-4, 10A-5, 10A-6. From among these ring nodes, 10A-6 gathers the data of the ring system A and is used as a line-gathering/relaying node that relays signals to an external circuit 14.
In like manner, ring system B comprises six ring nodes 10B-1, 10B-2, 10B-3, 10B-4, 10B-5, 10B-6 and ring system C comprises six ring nodes 10C-1, 10C-2, 10C-3, 10C-4, 10C-5, 10C-6. From among these ring nodes, 10B-6 gathers the data of ring system B and ring system C and is used as a line-gathering/relaying node that relays signals to an external circuit 14.
Furthermore, a relay switch 15 is connected to external circuit 14 for the purpose of relaying data from ring nodes 10A-6, 10B-6, 10C-6 of the line-gathering/relaying node to an exchange 40 through relay circuit 30.
As understood from the configuration shown in FIG. 33, in this conventional network system, one ring node (10A-6, 10B-6, 10C-6) from among each of the ring systems A, B, C was used for line-gathering and in addition, it was necessary to provide relay switch 15 to further gather the data.
According to this configuration, in addition to increasing the number of line-gathering nodes in response to the number of ring systems, each line-gathering node had to be arranged at a position where a relay is carried out which worsened the efficiency of the node utilization.
Furthermore, a case was also considered from the viewpoint of improved communication reliability for relay system that is doubled in the line-gathering/relaying of the data of a ring system. For this case however, specialized devices were necessary to control these doubled relay systems.
It has also been considered to use a ring system having the type of configuration shown in FIG. 32 in a railroad management system or a roadway management system. Because of this, particularly strong emphasis has been placed on communication reliability.
From the viewpoint of this type of improved communication reliability, when a fault occurs in this type of system, a loopback control function is normally provided that helps with communication by looping back the communication path using two ring nodes adjacent to the location where the fault occurred forming a communication path that bypasses the location where the fault occurred.
Moreover, this loopback control function is also utilized when expanding or reducing ring nodes.
FIG. 34 to FIG. 36 shows changes in of the loopback control when expanding the ring nodes in a conventional ring system. Further, the ring system of FIG. 34 to FIG. 36 may be considered to use camera 11A as local communication terminal 111 and to use monitor device 11B as local communication terminal 11-2 in the ring system shown in FIG. 32.
Normally, in this system, camera 11A (connected to ring node 10D) and monitor device 11B (connected to ring node 10E) communicate through clockwise communication path 61 set within transmission path 6. At this time, communication path 61 and counterclockwise communication path 62 are in reserve to control the loopback.
When an attempt is made to expand ring node 10F between, for example, ring node 10A and ring node 10B during communication between camera 11A and monitor device 11B, at first, a loopback instruction A is sent from control node 9 to ring node 10A as shown in FIG. 34. By means of receiving this loopback instruction A, ring node 10A implements a loopback between control node 9 such that communication path 61 returns to communication path 62.
Next, as shown in FIG. 35, control node 9 transmits a loopback instruction Axe2x80x2 to ring node 10B. By means of receiving this loopback instruction Axe2x80x2, ring node 10B implements a loopback between control node 9 such that communication path 62 returns to communication path 61.
After both ring node 10A and ring node 10B complete the loopback, expansion ring node 10F inserts between ring node 10A and ring node 10B as shown in FIG. 36 and forming a ring with additional ring node 10F. Thereafter, loopback release instruction is sent from control node 9 to both ring node 10A and ring node 10B. Because of this, ring node 10A and ring node 10B both release the loopback and clockwise communication path 61 is reset through expanded ring node 10F to complete the ring expansion operation.
As is understood from the description in FIG. 34 to FIG. 36, when expanding ring nodes in a conventional system, only the two ring nodes 10A, 10B adjacent to the node expansion location carried out the loopback to the control node 9 side and a loopback was not carried out in the side where ring node 10F is being expanded.
Thus, for example, communication path 61 between camera 11A and monitor device 11B was interrupted and communication between both was not allowed during the period between after ring node 10A in FIG. 34 carried out a loopback until ring node 10B in FIG. 35 completed a loopback.
Even if a loopback instruction was simultaneously transmitted to ring node 10A and ring node 10B, because each ring node 10A, 10B are operated by control programs independent of each other, a time difference would occur in the loopbacks and communication between camera 11A and monitor device 11B would be interrupted for the period corresponding to that difference.
Further, when reducing ring nodes, there was a control in which the two corresponding ring nodes would loopback and then the loopback would be released. For this case however, in a conventional system, wherein only the two ring nodes which received loopback instructions would carry out a loopback on the control node side 9, a communication interruption between camera 11A and monitor device 11B could not be avoided identical to when ring nodes are expanded.
Further, according to a conventional system, wherein a loopback was only carried out on one side, the communication path would still be in a momentary interruption state even if the loopback was released after, for example, recovering a fault and of course a communication interruption between camera 11A and monitor device 11B could not be avoided.
As described above, one construction mode of a communication network system in the fields of railroad management or a roadway management was a plurality of ring systems having the configuration as shown in FIG. 32.
In addition, when constructing this type of communication network system, the following configuration was considered ordinary.
Using one ring node for each of the ring systems as a line-gathering node and further providing a relay switch that relays data from these line-gathering nodes to a relay circuit.
To make the double relay systems, special devices are provided to control the switching of these relay systems.
Therefore, when constructing a network that covers a ring shaped region using the ring system, the necessity of arranging the ring nodes in contact with line-gathering nodes at positions where a relay is carried out worsened the efficiency of node utilization. In addition, there were problems of increasing complexity of the configuration and the unavoidable increases in cost.
Further, because the basic configuration in the conventional system is complex, it is difficult to achieve a configuration, wherein a relay system is doubled and even if it could be obtained, specialized devices were necessary to control these doubled relay systems with a problem of further increases in system cost.
Moreover, in a conventional communication network system that utilizes the ring system shown in FIG. 32, irregardless of whether this ring system was a single unit or a plurality of units, a loopback would only be carried out on the side that received a loopback instruction in the two ring nodes which received a loopback instruction when the ring nodes were being expanded, reduced or when a fault was being restored. A loopback was not carried out on the side where the ring nodes were being expanded, reduced or where a fault was being restored.
When ring nodes were being expanded, reduced or when a fault was being restored during communication between arbitrary local communication terminals, the communication path between the local communication terminals would be in a momentary interruption during the period between after one of the ring nodes started a loopback until the another ring node completed a loopback (or the period between after one of the ring nodes started loopback release until the another ring node completed loopback release) resulting in a problem of communication between the local communication terminals being interrupted.
The first object of the present invention is to provide a communication network system that does not require line-gathering nodes for each of the ring systems as well as simplifies the configuration and reduces the cost when constructing a system using a plurality of ring systems.
A second object of the present invention is to provide a communication network system that can simplify the double construction of the relay system as well as simplify the method to switch the doubled relay system when constructing a system using a plurality of ring systems.
A third object of the present invention is to provide a communication network system and loopback control method that can deal with expansion and reduction or fault restoration of node devices without interrupting communication between local communication terminals within ring systems.
In order to achieve the third object, the invention of claim 1 is a communication network system, wherein a plurality of node devices and a control node device that controls this plurality of node devices are connected in a ring shape by means of the ring circuits that can set a first communication path and a second communication path in a direction opposite to the first communication path and that during normal operation carries out transmission of data through the first communication path between each of the node devices or between communication terminals connected to each of the node devices. Furthermore, the control node device comprises a loopback control instruction method that issues loopback instructions or loopback release instructions to an arbitrary node device and each of the node devices comprise loopback control methods which loopback the first communication path to the second communication path on both the left and right sides of the ring circuits as seen from the devices themselves based on the loopback instructions and which also release the loopback based on the loopback release instructions.
In the invention of claim 1, the invention of claim 2 is characterized by being further comprised by a terminal management device that is connected to a control node device and this terminal management device comprises an instruction method that instructs a loopback request or loopback release request together with the name of the request target node device to the control node device and in addition the control node device issues a loopback instruction or loopback release instruction to applicable node devices within a ring based on the instructions from the terminal management device.
In the invention of claim 2, the invention of claim 3 is characterized by a terminal management device executing the following procedures when node devices are expanded within the rings; a first expansion procedure that carries out the loopback request for one node device out of two node devices adjacent to the expansion location that should undergo loopback control, a second expansion procedure that carries out the loopback request for the other node device out of two node devices that should undergo loopback control, a third expansion procedure that carries out the loopback release request for a node device that previously received the loopback request and should undergo loopback release after the expansion operation of the expansion target node device competes, and a fourth expansion procedure that carries out the loopback release request for a node device that subsequently received the loopback request and should undergo loopback release.
In the invention of claim 2, the invention of claim 4 is characterized by a terminal management device executing the following procedures when node devices are reduced within the rings; a first reduction procedure that carries out the loopback request for one node device out of two node devices adjacent to the reduction location that should undergo loopback control, a second reduction procedure that carries out the loopback request for the other node device out of two node devices that should undergo loopback control, a third reduction procedure that carries out the loopback release request for a node device that previously received the loopback request and should undergo loopback release after the expansion operation of the reduction target node device competes, and a fourth reduction procedure that carries out the loopback release request for a node device that subsequently received the loopback request and should undergo loopback release.
In the invention of claim 2, the invention of claim 5 is characterized by a terminal management device executing the following procedures when a fault occurs in node devices within the rings; a first fault restoration procedure that carries out the loopback request for one node device out of two node devices adjacent to the location where the fault occurred that should undergo loopback control, a second fault restoration procedure that carries out the loopback request for the other node device out of two node devices that should undergo loopback control, a third fault restoration procedure that carries out the loopback release request for a node device that previously received the loopback request and should undergo loopback release after the fault recovering operation of the node device where a fault occurred competes, and a fourth fault restoration procedure that carries out the loopback release request for a node device that subsequently received the loopback request and should undergo loopback release.
In the invention of claim 1, the invention of claim 6 is characterized by the ring circuits comprising an asynchronous transfer mode (ATM) circuit that can set virtual paths of two levels of virtual paths (VP) and virtual channels (VC). This invention is further characterized by a node device being comprised by an ATM switching device that switches and outputs an ATM cell (input from the transmission path to an input port) to the transmission path through an output port in accordance with a virtual path identifier and a virtual channel identifier contained within the ATM cell.
In the invention of claim 1, the invention of claim 7 is characterized by the ring circuits being formed by a wire circuit.
In the invention of claim 1, the invention of claim 8 is characterized by the ring circuits formed by a radio circuit.
Furthermore, the invention of claim 9 is a method, wherein a plurality of node devices and a control node device that controls this plurality of node devices are connected in a ring shape by means of the ring circuits that can set a first communication path and a second communication path in a direction opposite to the first communication path and that during normal operation carries out transmission of data through the first communication path between each of the node devices or between communication terminals connected to each of the node devices and even further is a method that carries out a loopback and loopback release between the first communication path and the second communication path. Loopback instructions or loopback release instructions are issued to an arbitrary node device from the control node device and each of the node devices are arranged such that they loopback the first communication path to the second communication path on both the left and right sides of the rings as seen from the devices themselves based on the loopback instructions and which also release the loopback based on the loopback release instructions.
In the invention of claim 9, the invention of claim 10 is characterized by being further comprised by a terminal management device that is connected to a control node device and this terminal management device instructs a loopback request or loopback release request together with the name of the request target node device to the control node device and in addition the control node device issues a loopback instruction or loopback release instruction to applicable node devices within a ring based on the instructions from the terminal management device.
In the invention of claim 10, the invention of claim 11 is characterized by a terminal management device executing the following procedures when node devices are expanded within the rings; a first expansion procedure that carries out the loopback request for one node device out of two node devices adjacent to the expansion location that should undergo loopback control, a second expansion procedure that carries out the loopback request for the other node device out of two node devices that should undergo loopback control, a third expansion procedure that carries out the loopback release request for a node device that previously received the loopback request and should undergo loopback release after the expansion operation of the expansion target node device competes, and a fourth expansion procedure that carries out the loopback release request for a node device that subsequently received the loopback request and should undergo loopback release.
In the invention of claim 10, the invention of claim 12 is characterized by a terminal management device executing the following procedures when node devices are reduced within the rings; a first reduction procedure that carries out the loopback request for one node device out of two node devices adjacent to the reduction location that should undergo loopback control, a second reduction procedure that carries out the loopback request for the other node device out of two node devices that should undergo loopback control, a third reduction procedure that carries out the loopback release request for a node device that previously received the loopback request and should undergo loopback release after the expansion operation of the reduction target node device competes, and a fourth reduction procedure that carries out the loopback release request for a node device that subsequently received the loopback request and should undergo loopback release.
In the invention of claim 10, the invention of claim 13 is characterized by a terminal management device executing the following procedures when a fault occurs in node devices within the rings; a first fault restoration procedure that carries out the loopback request for one node device out of two node devices adjacent to the location where the fault occurred that should undergo loopback control, a second fault restoration procedure that carries out the loopback request for the other node device out of two node devices that should undergo loopback control, a third fault restoration procedure that carries out the loopback release request for a node device that previously received the loopback request and should undergo loopback release after the fault recovering operation of the node device where a fault occurred competes, and a fourth fault restoration procedure that carries out the loopback release request for a node device that subsequently received the loopback request and should-undergo loopback release.
In the invention of claim 9, the invention of claim 14 is characterized by the ring circuits comprising an asynchronous transfer mode (ATM) circuit that can set virtual paths of two levels of virtual paths (VP) and virtual channels (VC). This invention is further characterized by a node device being comprised by an ATM switching device that switches and outputs an ATM cell (input from the transmission path to an input port) to the transmission path through an output port in accordance with a virtual path identifier and a virtual channel identifier contained within the ATM cell.
According to the inventions of claim 1 to claim 14, because two node devices which received loopback instructions are provided with an x type loopback function that carries out loopbacks for communication paths on both the left and right sides of the rings, even if a time difference occurs in a loopback or loopback release when carrying out a loopback in two node devices or when releasing that loopback, the current communication path will not be interrupted. Therefore, by means of utilizing this x type loopback function, it is possible to deal with expansion and reduction or fault restoration of node devices without interrupting communication.